All-solid waste cementing material stabilized macadam base mixture

Abstract

The invention discloses an all-solid-waste cementing material stabilized macadam base mixture which is prepared from the following raw materials in parts by weight: 4-6 parts of an all-solid-waste cementing material, 0-6 parts of wet-discharged fly ash, 0-20 parts of silicon-manganese slag, 10-20 parts of steel slag, 52-65 parts of macadam and 4-6 parts of water. The moisture content of the wet discharged fly ash is 8-12%. According to the all-solid waste cementing material stabilized macadam base mixture provided by the invention, the characteristics of low heat, micro-expansion and relatively high water demand of the all-solid waste cementing material can be utilized, agglomeration of wet-discharged fly ash is reduced, and the uniformity of the water stabilized base mixture is improved, so that the hydration heat is reduced, the risk of quick setting and shrinkage cracking is reduced, meanwhile, the solid waste utilization rate is increased, and the production cost is reduced. And the production cost and the carbon emission are reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of road engineering materials, and in particular, relates to a full-solid-waste cementitious material stabilized macadam base mixture. BACKGROUND

[0002] The cement stabilized road base refers to a road base formed by mixing, paving and compacting soil or sand and gravel or other aggregates with cement as a binder and water.

[0003] Due to the characteristics of traditional Portland cement, such as fast hydration speed and large hydration heat, the road base paved with the traditional Portland cement is prone to fast setting in areas with high temperature and strong wind in summer, which leads to the failure to compact in time. If the compaction is forced, the skeleton structure formed by cement hydration will be damaged, and the mechanical properties and road performance of the road base will be affected. Meanwhile, the high hydration heat is prone to cause shrinkage cracking of the road surface, affecting the construction quality.

[0004] In addition, with the rising prices of cement and sand and gravel materials, the construction cost gradually increases. At the same time, the vigorous development of various metallurgical industries and power industries leads to the accumulation of silicon manganese slag, steel slag and wet-discharged fly ash, and it is urgent to find a good treatment method to solve the environmental pressure caused by the land occupation and discharge of industrial solid waste. SUMMARY

[0005] The technical problem to be solved by the application is to provide a full-solid-waste cementitious material stabilized macadam base mixture to solve the problems in the background.

[0006] To achieve the above technical problem, the application provides a full-solid-waste cementitious material stabilized macadam base mixture, which is composed of the following raw materials in parts by weight: full-solid-waste cementitious material 4-6 parts, wet-discharged fly ash 0-6 parts, silicon manganese slag 0-20 parts, steel slag 10-20 parts, macadam 52-65 parts and water 4-6 parts; the moisture content of the wet-discharged fly ash is 8-12%.

[0007] In this scheme, by using the full-solid-waste cementitious material to replace the traditional Portland cement, the low heat, micro-expansion and high water demand characteristics of the full-solid-waste cementitious material are utilized to reduce the agglomeration of the wet-discharged fly ash and improve its dispersion capacity, thereby reducing the hydration heat and reducing the risk of fast setting and shrinkage cracking. The moisture content of 8-12% of the wet-discharged fly ash can improve the uniformity of the water stabilized base mixture and avoid excessive local moisture, which causes water loss cracking. In addition, compared with the traditional fly ash, the direct use of wet-discharged fly ash reduces the drying process and reduces the production cost and carbon emissions.

[0008] Further, the wet-discharged fly ash is obtained by the following steps: adding alkyl polyoxyethylene ether with a concentration of 0.003%-0.005% into the fly ash after wet treatment and mixing uniformly; adding hydroxyethyl methyl cellulose with a concentration of 0.001%-0.003% into the mixed fly ash and mixing fully to obtain the wet-discharged fly ash.

[0009] In this scheme, the alkyl polyoxyethylene ether mainly solves the problems of agglomeration, poor dispersibility and unevenness of the fly ash after wet treatment; the introduction of hydroxyethyl methyl cellulose mainly reduces the water content of the wet-discharged fly ash, improves the uniformity of the water-stable base mixture, and avoids excessive local moisture, which causes water loss and cracking.

[0010] As a better option, the steel slag includes modified steel slag with a particle size of 5-10 mm, and the free calcium oxide in the modified steel slag is less than 2.0%.

[0011] Further, the modified steel slag is obtained by the following steps: mixing the steel slag and tricalcium silicate uniformly at a mass ratio of 1:30, adding into a granulator, spraying water with a solid mass of 8-12% into the granulator, aging for 1-3 h to obtain first steel slag; spraying sodium silicate solution into the first steel slag, aging for 1-2 h to obtain second steel slag; the spraying amount of the sodium silicate solution is 4-8%; adding silica fume with a mass of 1-3% of the steel slag into the second steel slag, and supplementing water with a solid mass of 8-12%, and continuing to age for 1-3 h to obtain third steel slag; drying the third steel slag in a drying oven at 60-80℃ for 6-12 h to obtain modified steel slag.

[0012] In this scheme, by using modified steel slag with free calcium oxide content less than 2.0%, the problems of volume expansion and poor stability caused by the hydration of free calcium oxide in the application of steel slag are effectively solved, and the road performance and engineering applicability of the steel slag are significantly improved. Through a specific modification process, the steel slag is mixed with tricalcium silicate to induce free calcium oxide to continue to hydrate to generate more calcium hydroxide, sodium silicate solution is added to promote the generation of hydrated calcium silicate gel, and silica fume is introduced to further consume the generated calcium hydroxide to generate more hydrated calcium silicate gel, promote the generation of hydrated calcium silicate gel, and further promote the dissolution and hydration of free calcium oxide in the steel slag, thereby effectively inhibiting the water immersion expansion and autoclaved pulverization of the steel slag, reducing the hydration heat and rapid setting phenomenon, avoiding the cracking problem caused by expansion, and improving the workability and road performance of the base. The iron oxide contained in the modified steel slag can further improve the wear resistance of the pavement base.

[0013] Further, the water immersion expansion rate of the modified steel slag is less than 2.0%, and the autoclaved pulverization rate is less than 5.0%.

[0014] As a preferred option, the composition of the full solid waste cementitious material comprises 10-20% of industrial by-product gypsum, 40-70% of slag, 0-20% of fly ash or coal gangue, and 0-20% of other raw materials; the other raw materials include carbide slag, steel slag, and cement.

[0015] As a preferred option, the silicon manganese slag comprises silicon manganese slag with a particle size of 0-5mm; the organic matter content of the silicon manganese slag is less than 2%, and the sulfate content of the silicon manganese slag is not more than 0.25%.

[0016] As a preferred option, the crushed stone comprises 32-38 parts of crushed stone with a particle size of 10-20mm and 20-27 parts of crushed stone with a particle size of 20-30mm.

[0017] Further, the crushing value of the crushed stone is not more than 26%.

[0018] The beneficial effects of the present application are: 1. The scheme of the present application replaces traditional Portland cement with full solid waste cementitious material, takes advantage of the low heat, micro-expansion, and high water demand characteristics of full solid waste cementitious material, reduces the agglomeration of wet-discharged fly ash, and improves its dispersion capacity, thereby reducing the hydration heat, reducing the risk of rapid setting and shrinkage cracking. The water content of wet-discharged fly ash is 8-12%, which can improve the uniformity of water stable base mixture and avoid excessive local water content, which can cause water loss cracking. In addition, compared with traditional fly ash, direct use of wet-discharged fly ash reduces the drying process, reduces production costs and carbon emissions.

[0019] 2. The scheme of the present application uses modified steel slag with free calcium oxide content less than 2.0%, effectively solves the problem of volume expansion and poor stability caused by free calcium oxide hydration in the application of steel slag, and significantly improves the road performance and engineering applicability of steel slag. Through a specific modification process, the steel slag is mixed with tricalcium silicate to induce free calcium oxide to continue to hydrate to generate more calcium hydroxide, sodium silicate solution is added to promote the generation of calcium silicate gel, and silica ash is introduced to further consume the generated calcium hydroxide to generate more calcium silicate gel, promote the generation of calcium silicate gel, further promote the dissolution and hydration of free calcium oxide in steel slag, thereby effectively inhibiting the water swelling and autoclaved powderization of steel slag, avoiding the cracking problem caused by the expansion of steel slag, and improving the workability and road performance of the pavement base. In addition, the iron oxide contained in the modified steel slag can further improve the wear resistance of the pavement base.

[0020] 3. The scheme of the present application takes advantage of the porous structure of silicon manganese slag, which can store more water, and can avoid the problem that the base mixture is not fully hydrated due to the delay of watering maintenance during rush construction, affecting the strength of the base and prolonging the construction progress. DETAILED DESCRIPTION

[0021] The embodiments of the technical solutions of the present application will be described in detail below. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0022] Preparation of wet-discharged fly ash - Example 1 It should be noted that the fly ash treated by wet method used in the following examples and comparative examples in step S1 has a water content of 18%.

[0023] Example 1-1 S11: 4 parts of alkyl polyoxyethylene ether with a concentration of 0.003% were added to 1000 parts of fly ash treated by wet method, and mixed uniformly; S12: 3 parts of hydroxyethyl methyl cellulose were added to the mixture in S11, and after being mixed thoroughly, wet-discharged fly ash was obtained.

[0024] Examples 1-2~1-3 Examples 1-2~1-3 are different from Example 1-1 in that the control conditions of each step are different, and the specific control conditions are shown in Table 1.

[0025] Comparative Examples 1-1~1-3 Comparative Example 1-1 is different from Example 1-1 in that hydroxyethyl methyl cellulose is directly added to fly ash in Comparative Example 1-1, and step S11 is not performed. Comparative Examples 1-2~1-3 are different from Example 1-1 in that the control conditions of hydroxyethyl methyl cellulose are different, and the specific control conditions are shown in Table 1.

[0026] Table 1 Control conditions for preparation of wet-discharged fly ash examples and comparative examples According to the “Highway Engineering Inorganic Stabilized Material Test Regulations” (JTG3441-2024), the water content of the wet-discharged fly ash prepared in each example and comparative example in Table 1 was determined, and the particle size distribution was observed, and the specific results are shown in Table 2.

[0027] Table 2 Water content determination results of wet-discharged fly ash prepared in examples and comparative examples Preparation of modified steel slag - Example 2 Example 2-1 S21: The steel slag and tricalcium silicate were mixed uniformly at a mass ratio of 1:30, then added to a granulator, 10% solid water was sprayed into the granulator, and aged for 2h to obtain a first steel slag; S22: spraying a sodium silicate solution with a concentration of 20% into the first steel slag, aging for 2h to obtain a second steel slag; the spraying amount of the sodium silicate solution is 6%; S23: adding silica fume with a mass of 3% of the steel slag to the second steel slag, and supplementing water with a solid mass of 8%, and continuing to age for 3h to obtain a third steel slag; S24: drying the third steel slag in a drying box at 70℃ for 9h to obtain a modified steel slag.

[0028] Example 2-2 Example 2-2 differs from Example 2-1 in that the control conditions of each step are different, and the specific control conditions are shown in Table 3.

[0029] Comparative Examples 2-1~2-2 Comparative Example 2-1 differs from Example 1-1 in that no tricalcium silicate is added in step S21; Comparative Example 2-2 differs from Example 1-1 in that no sodium silicate solution is added in step S22.

[0030] Table 3 Control conditions for preparing modified steel slag of examples and comparative examples According to the Determination of Free Calcium Oxide Content in Steel Slag-EDTA Titration and Thermogravimetric Analysis Method (GB / T 38216.3-2023) and Steel Slag Stability Test Method (GB / T 24175-2009), the free calcium oxide content, water immersion expansion rate and autoclaved pulverization rate of the modified steel slag prepared in each example and comparative example in Table 3 were determined, and the specific results are shown in Table 4.

[0031] Table 4 Determination results of each parameter of modified steel slag prepared in examples and comparative examples Preparation of full-solid-waste cementitious material stabilized gravel base mixture-Example 3 Example 3-1 The full-solid-waste cementitious material stabilized gravel base mixture was obtained by fully mixing 4 parts of full-solid-waste cementitious material, 0 parts of wet fly ash prepared in Example 1-1, 10 parts of silicon-manganese slag, 10 parts of steel slag, 65 parts of gravel (31 parts of 10-20mm gravel and 34 parts of 20-30mm gravel), and 4 parts of water.

[0032] It should be noted that the full-solid-waste cementitious material used in the following specific examples is the full-solid-waste cementitious material of type II in the DB 64 / T 2004-2024 standard.

[0033] Examples 3-2~3-5 Examples 3-2 to 3-5 differ from Example 3-1 in that the control conditions of each step are different, and the specific control conditions are shown in Table 5.

[0034] Comparative Examples 3-1 to 3-4 Comparative Example 3-1 differs from Example 3-1 in that Comparative Example 3-1 uses Portland cement P·O 42.5 to replace the full solid waste cementitious material; Comparative Examples 3-2 to 3-4 differ from Example 3-1 in that the types and mass parts of the components are different, and the specific control conditions are shown in Table 5.

[0035] Table 5 Control conditions for preparing full solid waste cementitious material stabilized gravel base mixture examples and comparative examples The full solid waste cementitious material stabilized gravel base mixtures obtained from Examples 3-1 to 3-5 and Comparative Examples 3-1 to 3-6 are tested for road performance, mechanical performance, etc. according to the “Test Code for Inorganic Binder Stabilized Materials of Highway Engineering” (JTG3441-2024). The compressive strength of the full solid waste cementitious material stabilized gravel base mixture is determined according to the “Technical Details for Highway Pavement Base Construction” (JTGT F20-2015) guidelines. The 7d unconfined compressive strength after standard curing is measured immediately after compaction, after 2h, 4h and 6h of curing, respectively, to obtain the compressive strength of the delayed 0h, 2h, 4h and 6h. The specific performance test results are shown in Table 6.

[0036] Table 6 Performance test results of full solid waste cementitious material stabilized gravel base mixtures obtained from Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-3 Experimental conclusions: From the experimental results of Examples 3-1 to 3-5 and Comparative Example 3-1 above, it can be seen that the mixture prepared using the full solid waste cementitious material in Examples 3-1 to 3-5 has a significant improvement in compressive strength and dry shrinkage coefficient compared to the mixture prepared using Portland cement in Comparative Example 3-1. In particular, Example 3-4 has a 57.5% improvement in delayed 6h compressive strength, a 15.7% improvement in freeze-thaw compressive strength, and a 35.6% reduction in dry shrinkage coefficient compared to Comparative Example 3-1. It is speculated that the full solid waste cementitious material significantly alleviates the rapid setting phenomenon and inhibits shrinkage cracking through its low heat and micro-expansion properties, while also improving the freeze-thaw durability.

[0037] From the experimental results of Examples 3-2~3-3 and Comparative Examples 3-2~3-4, it can be seen that the wet-discharged fly ash treated by alkyl polyoxyethylene ether and hydroxyethyl methyl cellulose in cooperation significantly improves the mechanical properties of the mixture compared with the comparative examples without adding alkyl polyoxyethylene ether or hydroxyethyl methyl cellulose. The compressive strength of Examples 3-2~3-3 is not less than 5.1 MPa, and the splitting strength is not less than 0.56 MPa, which is obviously improved compared with the compressive strength of not more than 4.9 MPa and the splitting strength of not more than 0.51 MPa of Comparative Examples 3-2~3-4. At the same time, the dry shrinkage coefficient of Examples 3-2~3-3 is obviously lower than that of Comparative Examples 3-2~3-4, indicating that the optimization of the dispersibility of the wet-discharged fly ash effectively inhibits the shrinkage cracking caused by uneven water distribution.

[0038] From the experimental results of Examples 3-4~3-5 and Comparative Examples 3-5~3-6, it can be seen that the free calcium oxide content and water immersion expansion rate of the steel slag treated by tricalcium silicate induced hydration and sodium silicate / silica ash in cooperation are significantly lower than those of the untreated steel slag. The change of the 6h delayed compressive strength of Examples 3-4~3-5 is significantly lower than that of Comparative Examples 3-5~3-6, and the dry shrinkage coefficient is obviously lower than that of the comparative examples, verifying the improvement of the volume stability of the modified steel slag.

[0039] Therefore, through the dispersibility regulation of wet-discharged fly ash, the stability modification of steel slag, and the synergistic effect of full solid waste cementitious materials, the application realizes the performance of high-strength, low-shrinkage, and freeze-thaw resistant pavement base material, and realizes the resource utilization of industrial solid waste.

[0040] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A solid waste cementitious material stabilized crushed stone base course mixture, characterized in that, It is composed of the following raw materials in parts by weight: 4-6 parts of solid waste cementitious material, 0-6 parts of wet fly ash, 0-20 parts of ferrosilicon manganese slag, 10-20 parts of steel slag, 52-65 parts of crushed stone, and 4-6 parts of water; the moisture content of the wet fly ash is 8-12%.

2. The all-solid waste cementitious material stabilized crushed stone base mixture as described in claim 1, characterized in that, The wet fly ash is obtained through the following steps: Add 0.003%-0.005% alkyl polyoxyethylene ether to the wet-treated fly ash and mix thoroughly. Add 0.001%-0.003% hydroxyethyl methyl cellulose to the mixed fly ash, and mix thoroughly to obtain wet fly ash.

3. The all-solid waste cementitious material stabilized crushed stone base mixture as described in claim 1, characterized in that, The steel slag includes modified steel slag with a particle size of 5-10 mm, and the free calcium oxide in the modified steel slag is less than 2.0%.

4. The all-solid waste cementitious material stabilized crushed stone base mixture as described in claim 3, characterized in that, The modified steel slag is obtained through the following steps: Steel slag and tricalcium silicate are mixed evenly at a mass ratio of 1:30 and then added to a granulator. Water of 8-12% of the solid mass is sprayed into the granulator and aged for 1-3 hours to obtain the first steel slag. A sodium silicate solution is sprayed into the first steel slag, and the slag is aged for 1-2 hours to obtain a second steel slag; the amount of sodium silicate solution sprayed is 4-8%. Add 1-3% silica fume by weight of the steel slag to the second steel slag, and add 8-12% water by weight of solids, and continue aging for 1-3 hours to obtain the third steel slag; The third steel slag is dried in a drying oven at 60-80℃ for 6-12 hours to obtain modified steel slag.

5. A solid waste cementitious material stabilized crushed stone base course mixture as described in claim 3 or 4, characterized in that, The modified steel slag has a water immersion expansion rate of less than 2.0% and a pressure steam pulverization rate of less than 5.0%.

6. The all-solid waste cementitious material stabilized crushed stone base course mixture as described in claim 1, characterized in that, The composition of the all-solid waste cementitious material includes: 10-20% industrial by-product gypsum, 40-70% slag, 0-20% fly ash or coal gangue, and 0-20% other raw materials; the other raw materials include carbide slag, steel slag, and cement.

7. The all-solid waste cementitious material stabilized crushed stone base course mixture as described in claim 1, characterized in that, The ferrosilicon slag includes ferrosilicon slag with a particle size of 0-5 mm; the organic matter content of the ferrosilicon slag is less than 2%, and the sulfate content of the ferrosilicon slag is not greater than 0.25%.

8. The all-solid waste cementitious material stabilized crushed stone base mixture as described in claim 1, characterized in that, The crushed stone comprises 32-38 parts of crushed stone with a particle size of 10-20 mm and 20-27 parts of crushed stone with a particle size of 20-30 mm.

9. The all-solid waste cementitious material stabilized crushed stone base mixture as described in claim 8, characterized in that, The crushing value of the crushed stone is no greater than 26%.

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